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Phylum Platyhelminthes

Phylum Platyhelminthes. Classes: Flatworms (Turbellaria) Flukes (Trematoda) Tapeworms (Cestoda) Monogeneans. They are Acoelomates because they lack body cavity (Coelom). This gives them a flat body structure (Flat worms). Flatworm Body Plans.

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Phylum Platyhelminthes

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  1. Phylum Platyhelminthes Classes: Flatworms (Turbellaria) Flukes (Trematoda) Tapeworms (Cestoda) Monogeneans Phylum Platyhelminthes

  2. They are Acoelomates because they lack body cavity (Coelom). • This gives them a flat body structure (Flat worms) Phylum Platyhelminthes

  3. Flatworm Body Plans • Exhibit bilateral symmetry, acoelomate, and are triploblastic • Parenchyma tissue Phylum Platyhelminthes

  4. Taxonomic Summary Phylum Platyhelminthes

  5. Phylum Platyhelminthes

  6. CHARACTERISTICS • BILATERAL SYMMETRY • THREE GERM LAYERS (TRIPLOBLASTIC) • CENTRALIZED NERVOUS SYSTEM • SIMPLE EXCRETORY SYSTEM • COMPLEX REPRODUCTIVE SYSTEM • SIMPLE DIGESTIVE SYSTEM Phylum Platyhelminthes

  7. Reproduction • Almost all are simultaneous hermaphrodites • Parasitic species (flukes and tapeworms) have complex lifecycles, with various hosts and several different larval stages • Incredible powers of regeneration Phylum Platyhelminthes

  8. Nervous System • Free-living species usually have a well-developed sensory system • Parasites generally have less elaborate systems. WHY? Phylum Platyhelminthes

  9. Class Turbellaria • Most are free–living, tiny and inconspicuous • Primarily marine and freshwater • e.g Planaria Free-living Flatworm Phylum Platyhelminthes

  10. Digestion and Excretion • Mouth is usually located at the anterior end or mid-body on ventral surface • Excretory system • Contains flame bulbs known as flame cell. Phylum Platyhelminthes

  11. Regeneration • Many species posses remarkable powers of regeneration and repair wounds Phylum Platyhelminthes

  12. Turbellarian Lifestyles • Most are benthic • Posses several nerve cords with a centralized ganglia (brain) Phylum Platyhelminthes

  13. Reproduction • Reproduction occurs with the reciprocal exchange of sperm. • Fertilized eggs are released and usually develop directly into flatworms • Muller's larva Phylum Platyhelminthes

  14. Defining characteristics Scolex Proglottids All parasitic E.g Taenia saginatta (beef tapeworm) Taenia solium (pork tapeworm) Class Cestoda (Tapeworms) Phylum Platyhelminthes

  15. Proglottids • Proglottids • Each animal can be 3,000 – 4,000 per animal • Amazing reproductive output • Each may contain several ovaries and 1,000 distinct testes Phylum Platyhelminthes

  16. Phylum Platyhelminthes

  17. Class Trematoda (Flukes) • All are external and internal parasites of other animals. • Leech-like bodies with a sucker at each end. • Have a gut and well-developed reproductive system, never segmented. • Blood flukes (Shistosomes),Liver flukes (Fasciola) & Lung flukes (Paragonimus) Phylum Platyhelminthes

  18. Schistosomes (Blood Fluke) • Causes infection known as Schistosomiasis (Formally Bilharziasis) • They are dioecious (Sexes are separted) • Adult males carry females in a gynaecophoric canal. Phylum Platyhelminthes

  19. Schistosome species Phylum Platyhelminthes

  20. Trematoda Lifecycles • The lifecycle is complex with up to 4 different hosts and several larval types Phylum Platyhelminthes

  21. Schistosomiasis Deadly prominent disease in many regions of the world Bores into the skin of the definitive host and travels in the circulatory system to the heart the lungs and the kidneys where it feeds and grows Inflammation is caused by eggs becoming trapped in the hosts tissues Chinese liver fluke Lives in the bile duct of humans, cats, and dogs (1-2 cm.) Goes through two intermediate hosts Infection occurs from ingestion of raw fish Life Cycle of Blood fluke (Schistosomes) Trematodes of Concern Phylum Platyhelminthes

  22. Liver Fluke (Fasciola) • Causes fascioliasis or liver rot in sheeps and dogs. • Major examples : F. Hepatica & F. Gigantica • Snail intermediate host- Lymnaea Phylum Platyhelminthes

  23. Life cycle of Liver fluke (Fasciola) Phylum Platyhelminthes

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